1. Field of the Invention
The present invention relates to a joint structure for coupling a pair of components in a joint portion of a fluid flow passage such as a fluid transport pipe and the like for transporting a fluid or gaseous material therethrough, and more particularly to such a joint structure for coupling the pair of components of the fluid flow passage in its joint portion in a seal-tight manner.
2. Description of the Related Art
In a fluid flow passage such as a fluid transport pipe and the like for transporting a fluid or gaseous material such as industrial chemicals in liquid or gas form, various types of paint, medicines and the like, there are provided various types of valves such as check valves and the like. On the other hand, a fluid container or reservoir is provided with a connector through which the fluid stored in the reservoir is delivered to the outside. These valves and the connector have joint portions. In each of the joint portions, a pair of components of the fluid flow passage are coupled to each other. In coupling these components to each other, it is necessary to couple the components to each other in a seal-tight manner in order to prevent the fluid being transported through the fluid flow passage from leaking out of the passage between these components.
As shown in FIG. 5, the connector, which is mounted on the fluid reservoir in order to deliver the fluid stored in the reservoir to the outside, is constructed of, for example: a plug member 31 in which a fluid communication valve 32 is incorporated, wherein the fluid communication valve 32 is opened when pushed inwardly from the outside; and, a housing 33 for receiving the plug member 31 therein. On the other hand, a socket member is mounted on a front end portion of an external hose, and detachably coupled with the plug member 31. More specifically, the socket member is constructed of: an inner sleeve in which a fluid communication valve is incorporated, wherein the fluid communication valve is opened when pushed inwardly from the outside; and, an outer sleeve in which the inner sleeve is incorporated, wherein the outer sleeve of the socket member is inserted into the housing 33 of the connector when the socket member mounted on the front end portion of the external hose is coupled to the connector mounted on the reservoir, so that the above two of the communication valves are pushed inwardly in opposite directions relative to each other to open, whereby the fluid may flow from the reservoir to the external hose through the connector and the socket member.
More specifically, the plug member 31 has a construction in which: mounted in the plug member 31 in an insertion manner is each of a compression coil spring 34 and a sealing nut 35, wherein the compression coil spring 34 is supported by the sealing nut 35. On the other hand, a siphon tube 36 is disposed under the sealing nut 35 and clamped firmly between the sealing nut 35 and a stopper member 37. Embedded in an inner wall of the plug member 31 is an O-ring 38, which is brought into press-contact with an outer circumferential wall of the sealing nut 35 to prevent the fluid from leaking out of the fluid communication valves in the fluid flow passage when the connector of the fluid reservoir is coupled with the socket member of the external hose.
The connector described above is of a conventional type. In this case, the siphon tube 36 has its upper end portion firmly clamped between the stopper member 37 and the sealing nut 35 to prevent the fluid from leaking out of the fluid communication valves. However, when the siphon tube 36 is frequently subjected to lateral loads as viewed in FIG. 5, a clamping force exerted by both the stopper member 37 and the sealing nut 35 on the upper end portion of the siphon tube 36 gradually decreases to eventually permit the stopper member 37 to rotate and loosen, which permits the fluid to leak out of the fluid flow passage.
Further, since the conventional connector uses the O-ring 38 for sealing a clearance between the plug member 31 and the sealing nut 35, it is necessary for a user of the conventional connector to manage maintenance of the O-ring 38. Furthermore, when the fluid to be transported through the fluid flow passage is an industrial chemical, for example such as one which is used in a semiconductor manufacturing process and capable of dissolving a coating layer of the O-ring 38 in the industrial chemical, there is a fear that the O-ring 38 contaminates the fluid with its coating layer in the semiconductor manufacturing process.
FIG. 6 shows a conventional check valve, which is constructed of: a female-side body 41; a male-side body 42 capable of being threadably engaged with an inner wall of the female-side body 41; and, a compression coil spring 44 for constantly urging a disk 43, wherein the compression coil spring 44 is received inside the male-side body 42. In this conventional check valve, the female-side body 41 has an inner flow passage 45 in its bottom area. In operation, the disk 43 keeps the inner flow passage 45 of the check valve in a closed state unless a fluid pressure in the inner flow passage 45 is equal to or more than a predetermined value.
In this case, in order to prevent the fluid from leaking out of the flow passage, an O-ring 46 is mounted in a clearance between the female-side body 41 and the male-side body 42 in an insertion manner. Further, by means of a locking pin 47 extending from an outer peripheral surface of the female-side body 41 to the male-side body 42, the male-side body 42 is prevented from rotating relative to the female-side body 41. Due to this, the conventional check valve is disadvantageous in that a large number of parts are required in manufacturing the conventional check valve. This makes it cumbersome to assembly these many parts into the check valve.
Although there is a simple assembly method for coupling two components by using a screw, the screw often loosens in use and therefore causes leakage of the fluid. In order to prevent such leakage of the fluid, it is necessary to manage frequent maintenance of such a screw, for example such as a periodical fastening operation of the screw.